This invention relates to a tube pressure filter.
Tube pressure filters are described, for example, in British Patent Specifications Nos. 907,485, 1,240,465 and 1,582,957, in British Patent Application No. 8301927, and in European Patent Specification No. 0036318. The inner assembly of a tube pressure filter generally comprises a central core and two end sections each of which has a sealing portion of diameter larger than the diameter of the central core, which portion closes one end of, and forms a seal with, an outer tubular assembly. A fairing is generally provided on each end section to effect a smooth change from the diameter of the sealing portion to the diameter of the central cylindrical section. The end sections also generally accommodate means for introducing a mixture of a particulate solid material and a liquid to be pressure filtered into the inner compartment of the tube pressure filter, means for removing filtrate which has passed through the filter element and means for introducing a compressed gas on the inner side of the filter element in order to assist the discharge of filter cake adhering to the outer side of the filter element.
The means for introducing the mixture to be pressure filtered into the inner compartment of the tube pressure filter generally comprises an annular orifice provided in the cuter surface of at least one of the fairings.
Hitherto the inner assembly of a tube pressure filter has been constructed by welding to each end of a tubular steel member, comprising the core, an inner end cap in the form of a substantially circular steel plate. An outer end cap, to which an annular member, comprising the fairing, is secured by a plurality of screws, is then secured to each inner end cap by means of a plurality of studs and nuts. This method of construction has the disadvantages that a fluid tight weld capable of withstanding high pressures must be effected in order to join the inner end caps to the tubular steel member, and a weld of this type is expensive to execute and must be carefully inspected, and also that a large number of nuts must be undone whenever the outer end cap is removed in order, for example, to change the wire mesh sleeve which supports the filter medium.